GCC Middle and Back End API Reference
tree-cfg.c File Reference

Data Structures

struct  cfg_stats_d
struct  locus_discrim_map
struct  locus_discrim_hasher
struct  label_record
struct  move_stmt_d


static void make_blocks (gimple_seq)
static void factor_computed_gotos (void)
static void make_edges (void)
static void assign_discriminators (void)
static void make_cond_expr_edges (basic_block)
static void make_gimple_switch_edges (basic_block)
static void make_goto_expr_edges (basic_block)
static void make_gimple_asm_edges (basic_block)
static edge gimple_redirect_edge_and_branch (edge, basic_block)
static edge gimple_try_redirect_by_replacing_jump (edge, basic_block)
static unsigned int split_critical_edges (void)
static bool stmt_starts_bb_p (gimple, gimple)
static int gimple_verify_flow_info (void)
static void gimple_make_forwarder_block (edge)
static gimple first_non_label_stmt (basic_block)
static bool verify_gimple_transaction (gimple)
static void gimple_merge_blocks (basic_block, basic_block)
static bool gimple_can_merge_blocks_p (basic_block, basic_block)
static void remove_bb (basic_block)
static edge find_taken_edge_computed_goto (basic_block, tree)
static edge find_taken_edge_cond_expr (basic_block, tree)
static edge find_taken_edge_switch_expr (basic_block, tree)
static tree find_case_label_for_value (gimple, tree)
void init_empty_tree_cfg_for_function ()
void init_empty_tree_cfg ()
static void build_gimple_cfg ()
static void replace_loop_annotate ()
static unsigned int execute_build_cfg ()
gimple_opt_passmake_pass_build_cfg ()
static bool computed_goto_p ()
static void make_blocks ()
static basic_block create_bb ()
void fold_cond_expr_cond ()
static int next_discriminator_for_locus ()
static bool same_line_p ()
static void make_cond_expr_edges ()
static bool edge_to_cases_cleanup (const void *key, void **value, void *data)
void start_recording_case_labels ()
static bool recording_case_labels_p ()
void end_recording_case_labels ()
static tree get_cases_for_edge ()
static void make_gimple_switch_edges ()
basic_block label_to_block_fn ()
void make_abnormal_goto_edges ()
static void make_goto_expr_edges ()
static void make_gimple_asm_edges ()
static tree main_block_label ()
static void cleanup_dead_labels_eh ()
void cleanup_dead_labels ()
void group_case_labels_stmt ()
void group_case_labels ()
static bool gimple_can_merge_blocks_p ()
void replace_uses_by ()
static void gimple_merge_blocks ()
basic_block single_noncomplex_succ ()
void notice_special_calls ()
void clear_special_calls ()
static void remove_phi_nodes_and_edges_for_unreachable_block ()
static void remove_bb ()
edge find_taken_edge ()
static edge find_taken_edge_computed_goto ()
static edge find_taken_edge_cond_expr ()
static edge find_taken_edge_switch_expr ()
static tree find_case_label_for_value ()
void gimple_debug_bb ()
basic_block gimple_debug_bb_n ()
void gimple_debug_cfg ()
void gimple_dump_cfg ()
void dump_cfg_stats ()
DEBUG_FUNCTION void debug_cfg_stats ()
static bool call_can_make_abnormal_goto ()
bool stmt_can_make_abnormal_goto ()
bool is_ctrl_stmt ()
bool is_ctrl_altering_stmt ()
bool simple_goto_p ()
static bool stmt_starts_bb_p ()
bool stmt_ends_bb_p ()
void delete_tree_cfg_annotations ()
gimple first_stmt ()
static gimple first_non_label_stmt ()
gimple last_stmt ()
gimple last_and_only_stmt ()
static void reinstall_phi_args ()
static basic_block split_edge_bb_loc ()
static basic_block gimple_split_edge ()
static tree verify_address ()
static tree verify_expr ()
static bool verify_types_in_gimple_min_lval ()
static bool verify_types_in_gimple_reference ()
static bool one_pointer_to_useless_type_conversion_p ()
static bool valid_fixed_convert_types_p ()
static bool verify_gimple_call ()
static bool verify_gimple_comparison ()
static bool verify_gimple_assign_unary ()
static bool verify_gimple_assign_binary ()
static bool verify_gimple_assign_ternary ()
static bool verify_gimple_assign_single ()
static bool verify_gimple_assign ()
static bool verify_gimple_return ()
static bool verify_gimple_goto ()
static bool verify_gimple_switch ()
static bool verify_gimple_debug ()
static bool verify_gimple_label ()
static bool verify_gimple_stmt ()
static bool verify_gimple_phi ()
static bool verify_gimple_in_seq_2 ()
static bool verify_gimple_transaction ()
DEBUG_FUNCTION void verify_gimple_in_seq ()
static bool tree_node_can_be_shared ()
static tree verify_node_sharing_1 ()
static tree verify_node_sharing ()
static int verify_eh_throw_stmt_node ()
static bool verify_location ()
static tree verify_expr_no_block ()
static tree verify_expr_location_1 ()
static tree verify_expr_location ()
static void collect_subblocks ()
DEBUG_FUNCTION void verify_gimple_in_cfg ()
static void gimple_make_forwarder_block ()
tree gimple_block_label ()
static edge gimple_try_redirect_by_replacing_jump ()
static edge gimple_redirect_edge_and_branch ()
static bool gimple_can_remove_branch_p ()
static basic_block gimple_redirect_edge_and_branch_force ()
static basic_block gimple_split_block ()
static bool gimple_move_block_after ()
static bool gimple_empty_block_p ()
static basic_block gimple_split_block_before_cond_jump ()
static bool gimple_can_duplicate_bb_p ()
static basic_block gimple_duplicate_bb ()
static void add_phi_args_after_copy_edge ()
void add_phi_args_after_copy_bb ()
void add_phi_args_after_copy (basic_block *region_copy, unsigned n_region, edge e_copy)
bool gimple_duplicate_sese_region (edge entry, edge exit, basic_block *region, unsigned n_region, basic_block *region_copy, bool update_dominance)
static bool bb_part_of_region_p ()
bool gimple_duplicate_sese_tail (edge entry, edge exit, basic_block *region, unsigned n_region, basic_block *region_copy)
void gather_blocks_in_sese_region (basic_block entry, basic_block exit, vec< basic_block > *bbs_p)
static void replace_by_duplicate_decl (tree *tp, struct pointer_map_t *vars_map, tree to_context)
static tree replace_ssa_name (tree name, struct pointer_map_t *vars_map, tree to_context)
static tree move_stmt_op ()
static int move_stmt_eh_region_nr ()
static tree move_stmt_eh_region_tree_nr ()
static tree move_stmt_r (gimple_stmt_iterator *gsi_p, bool *handled_ops_p, struct walk_stmt_info *wi)
static void move_block_to_fn (struct function *dest_cfun, basic_block bb, basic_block after, bool update_edge_count_p, struct move_stmt_d *d)
static eh_region find_outermost_region_in_block (struct function *src_cfun, basic_block bb, eh_region region)
static tree new_label_mapper ()
static void replace_block_vars_by_duplicates (tree block, struct pointer_map_t *vars_map, tree to_context)
static void fixup_loop_arrays_after_move (struct function *fn1, struct function *fn2, struct loop *loop)
basic_block move_sese_region_to_fn (struct function *dest_cfun, basic_block entry_bb, basic_block exit_bb, tree orig_block)
void dump_function_to_file ()
DEBUG_FUNCTION void debug_function ()
static void print_pred_bbs ()
static void print_succ_bbs ()
void print_loops_bb ()
static void print_loop_and_siblings (FILE *, struct loop *, int, int)
static void print_loop ()
void print_loops ()
DEBUG_FUNCTION void debug ()
DEBUG_FUNCTION void debug_verbose ()
DEBUG_FUNCTION void debug_loops ()
DEBUG_FUNCTION void debug_loop ()
DEBUG_FUNCTION void debug_loop_num ()
static bool gimple_block_ends_with_call_p ()
static bool gimple_block_ends_with_condjump_p ()
static bool need_fake_edge_p ()
static int gimple_flow_call_edges_add ()
void remove_edge_and_dominated_blocks ()
bool gimple_purge_dead_eh_edges ()
bool gimple_purge_all_dead_eh_edges ()
bool gimple_purge_dead_abnormal_call_edges ()
bool gimple_purge_all_dead_abnormal_call_edges ()
static void gimple_execute_on_growing_pred ()
static void gimple_execute_on_shrinking_pred ()
static void gimple_lv_adjust_loop_header_phi (basic_block first, basic_block second, basic_block new_head, edge e)
static void gimple_lv_add_condition_to_bb (basic_block first_head, basic_block second_head, basic_block cond_bb, void *cond_e)
static void gimple_account_profile_record (basic_block bb, int after_pass, struct profile_record *record)
gimple_opt_passmake_pass_split_crit_edges ()
tree gimplify_build3 (gimple_stmt_iterator *gsi, enum tree_code code, tree type, tree a, tree b, tree c)
tree gimplify_build2 (gimple_stmt_iterator *gsi, enum tree_code code, tree type, tree a, tree b)
tree gimplify_build1 (gimple_stmt_iterator *gsi, enum tree_code code, tree type, tree a)
static unsigned int execute_warn_function_return ()
void extract_true_false_edges_from_block (basic_block b, edge *true_edge, edge *false_edge)
gimple_opt_passmake_pass_warn_function_return ()
static void do_warn_unused_result ()
static unsigned int run_warn_unused_result ()
static bool gate_warn_unused_result ()
gimple_opt_passmake_pass_warn_unused_result ()
unsigned int execute_fixup_cfg ()
gimple_opt_passmake_pass_fixup_cfg ()
void gt_ggc_mx (tree &)
void gt_ggc_mx (gimple &)
void gt_ggc_mx (rtx &)
void gt_ggc_mx (basic_block &)
void gt_ggc_mx ()
void gt_pch_nx (tree &)
void gt_pch_nx (gimple &)
void gt_pch_nx (rtx &)
void gt_pch_nx (basic_block &)
void gt_pch_nx ()


static const int initial_cfg_capacity = 20
static struct pointer_map_tedge_to_cases
static bitmap touched_switch_bbs
static struct cfg_stats_d cfg_stats
static bool found_computed_goto
static hash_table
< locus_discrim_hasher
static struct label_recordlabel_for_bb
static bool eh_error_found
struct cfg_hooks gimple_cfg_hooks

Function Documentation

void add_phi_args_after_copy ( basic_block region_copy,
unsigned  n_region,
edge  e_copy 
   Blocks in REGION_COPY array of length N_REGION were created by
   duplication of basic blocks.  Add phi node arguments for edges
   going from these blocks.  If E_COPY is not NULL, also add
   phi node arguments for its destination.

Referenced by tm_memopt_clear_visited().

void add_phi_args_after_copy_bb ( )
   Basic block BB_COPY was created by code duplication.  Add phi node
   arguments for edges going out of BB_COPY.  The blocks that were
   duplicated have BB_DUPLICATED set.  
static void add_phi_args_after_copy_edge ( )
   Adds phi node arguments for edge E_COPY after basic block duplication.  
         During loop unrolling the target of the latch edge is copied.
         In this case we are not looking for edge to dest, but to
         duplicated block whose original was dest.  
static void assign_discriminators ( )
   Assign discriminators to each basic block.  

References loop::next.

static bool bb_part_of_region_p ( )
   Checks if BB is part of the region defined by N_REGION BBS.  
static void build_gimple_cfg ( )
   Entry point to the CFG builder for trees.  SEQ is the sequence of
   statements to be added to the flowgraph.  
     Register specific gimple functions.  
     Computed gotos are hell to deal with, especially if there are
     lots of them with a large number of destinations.  So we factor
     them to a common computed goto location before we build the
     edge list.  After we convert back to normal form, we will un-factor
     the computed gotos since factoring introduces an unwanted jump.  
     Make sure there is always at least one block, even if it's empty.  
     Adjust the size of the array.  
     To speed up statement iterator walks, we first purge dead labels.  
     Group case nodes to reduce the number of edges.
     We do this after cleaning up dead labels because otherwise we miss
     a lot of obvious case merging opportunities.  
     Create the edges of the flowgraph.  
static bool call_can_make_abnormal_goto ( )
   Return true if T, a GIMPLE_CALL, can make an abnormal transfer of control
   flow.  Transfers of control flow associated with EH are excluded.  
     If the function has no non-local labels, then a call cannot make an
     abnormal transfer of control.  
     Likewise if the call has no side effects.  
     Likewise if the called function is leaf.  
void cleanup_dead_labels ( void  )
   Cleanup redundant labels.  This is a three-step process:
     1) Find the leading label for each block.
     2) Redirect all references to labels to the leading labels.
     3) Cleanup all useless labels.  
     Find a suitable label for each block.  We use the first user-defined
     label if there is one, or otherwise just the first label we see.  
             If we have not yet seen a label for the current block,
             remember this one and see if there are more labels.  
             If we did see a label for the current block already, but it
             is an artificially created label, replace it if the current
             label is a user defined label.  
     Now redirect all jumps/branches to the selected label.
     First do so for each block ending in a control statement.  
               Replace all destination labels.  
           We have to handle gotos until they're removed, and we don't
           remove them until after we've created the CFG edges.  
     Do the same for the exception region tree labels.  
     Finally, purge dead labels.  All user-defined labels and labels that
     can be the target of non-local gotos and labels which have their
     address taken are preserved.  
         If the main label of the block is unused, we may still remove it.  

References gimple_asm_label_op(), and main_block_label().

static void cleanup_dead_labels_eh ( )
   Clean up redundant labels within the exception tree.  
void clear_special_calls ( void  )
   Clear flags set by notice_special_calls.  Used by dead code removal
   to update the flags.  
static void collect_subblocks ( )
   Insert all subblocks of BLOCK into BLOCKS and recurse.  
static bool computed_goto_p ( )
   Return true if T is a computed goto.  
static basic_block create_bb ( )
   Create and return a new empty basic block after bb AFTER.  
     Create and initialize a new basic block.  Since alloc_block uses
     GC allocation that clears memory to allocate a basic block, we do
     not have to clear the newly allocated basic block here.  
     Add the new block to the linked list of blocks.  
     Grow the basic block array if needed.  
     Add the newly created block to the array.  

References fold_binary_loc(), fold_defer_overflow_warnings(), fold_undefer_overflow_warnings(), gimple_cond_code(), gimple_cond_lhs(), gimple_cond_make_false(), gimple_cond_make_true(), gimple_cond_rhs(), gimple_location(), integer_onep(), integer_zerop(), last_stmt(), and WARN_STRICT_OVERFLOW_CONDITIONAL.

DEBUG_FUNCTION void debug ( )
   Dump a loop.  
DEBUG_FUNCTION void debug_cfg_stats ( void  )
   Dump CFG statistics on stderr.  Keep extern so that it's always
   linked in the final executable.  

References cfg_stats, gimple_label_label(), and cfg_stats_d::num_merged_labels.

DEBUG_FUNCTION void debug_function ( )
   Dump FUNCTION_DECL FN to stderr using FLAGS (see TDF_* in tree.h)  
DEBUG_FUNCTION void debug_loop ( )
   Print on stderr the code of LOOP, at some VERBOSITY level.  
DEBUG_FUNCTION void debug_loop_num ( )
   Print on stderr the code of loop number NUM, at some VERBOSITY
DEBUG_FUNCTION void debug_loops ( )
   Debugging loops structure at tree level, at some VERBOSITY level.  

References edge_def::flags.

DEBUG_FUNCTION void debug_verbose ( )
   Dump a loop verbosely.  
void delete_tree_cfg_annotations ( void  )
   Remove block annotations and other data structures.  
static void do_warn_unused_result ( )
   Walk a gimplified function and warn for functions whose return value is
   ignored and attribute((warn_unused_result)) is set.  This is done before
   inlining, so we don't have to worry about that.  
             This is a naked call, as opposed to a GIMPLE_CALL with an
             LHS.  All calls whose value is ignored should be
             represented like this.  Look for the attribute.  
             Not a container, not a call, or a call whose value is used.  

Referenced by gimple_purge_all_dead_abnormal_call_edges().

void dump_cfg_stats ( )
   Dump CFG statistics on FILE.  

Referenced by find_taken_edge_switch_expr().

void dump_function_to_file ( )
   Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in dumpfile.h)
     When GIMPLE is lowered, the variables are no longer available in
     BIND_EXPRs, so display them separately.  
         If the CFG has been built, emit a CFG-based dump.  
         The function is now in GIMPLE form but the CFG has not been
         built yet.  Emit the single sequence of GIMPLE statements
         that make up its body.  
         Make a tree based dump.  

References BUILT_IN_NORMAL, edge_def::flags, gimple_asm_input_p(), gimple_asm_volatile_p(), gimple_bb(), gimple_call_flags(), gimple_call_fndecl(), is_gimple_call(), and basic_block_def::succs.

Referenced by dump_maybe_newline().

static bool edge_to_cases_cleanup ( const void *  key,
void **  value,
void *  data 
   Called for each element in the hash table (P) as we delete the
   edge to cases hash table.

   Clear all the TREE_CHAINs to prevent problems with copying of
   SWITCH_EXPRs and structure sharing rules, then free the hash table
void end_recording_case_labels ( void  )
   Stop recording information mapping edges to case labels and
   remove any information we have recorded.  
static unsigned int execute_build_cfg ( )

References execute().

unsigned int execute_fixup_cfg ( void  )
   IPA passes, compilation of earlier functions or inlining
   might have changed some properties, such as marked functions nothrow,
   pure, const or noreturn.
   Remove redundant edges and basic blocks, and create new ones if necessary.

   This pass can't be executed as stand alone pass from pass manager, because
   in between inlining and this fixup the verify_flow_info would fail.  
         If we have a basic block with no successors that does not
         end with a control statement or a noreturn call end it with
         a call to __builtin_unreachable.  This situation can occur
         when inlining a noreturn call that does in fact return.  
     We just processed all calls.  
     Dump a textual representation of the flowgraph.  
static unsigned int execute_warn_function_return ( )
   Emit return warnings.  
     If we have a path to EXIT, then we do return.  
     If we see "return;" in some basic block, then we do reach the end
     without returning a value.  
void extract_true_false_edges_from_block ( basic_block  b,
edge true_edge,
edge false_edge 
   Given a basic block B which ends with a conditional and has
   precisely two successors, determine which of the edges is taken if
   the conditional is true and which is taken if the conditional is
   false.  Set TRUE_EDGE and FALSE_EDGE appropriately.  

Referenced by associate_equivalences_with_edges(), check_forbidden_calls(), operand_equal_for_value_replacement(), and simple_mem_ref_in_stmt().

static void factor_computed_gotos ( )
   Search the CFG for any computed gotos.  If found, factor them to a
   common computed goto site.  Also record the location of that site so
   that we can un-factor the gotos after we have converted back to
   normal form.  
     We know there are one or more computed gotos in this function.
     Examine the last statement in each basic block to see if the block
     ends with a computed goto.  
         Ignore the computed goto we create when we factor the original
         computed gotos.  
         If the last statement is a computed goto, factor it.  
             The first time we find a computed goto we need to create
             the factored goto block and the variable each original
             computed goto will use for their goto destination.  
                 Create the destination of the factored goto.  Each original
                 computed goto will put its desired destination into this
                 variable and jump to the label we create immediately
                 Build a label for the new block which will contain the
                 factored computed goto.  
                 Build our new computed goto.  
             Copy the original computed goto's destination into VAR.  
             And re-vector the computed goto to the new destination.  

References create_artificial_label(), create_empty_bb(), create_tmp_var(), gimple_build_goto(), gimple_build_label(), gsi_insert_after(), GSI_NEW_STMT, and gsi_start_bb().

static tree find_case_label_for_value ( gimple  ,
static tree find_case_label_for_value ( )
   Return the CASE_LABEL_EXPR that SWITCH_STMT will take for VAL.
   We can make optimal use here of the fact that the case labels are
   sorted: We can do a binary search for a case matching VAL.  
         Cache the result of comparing CASE_LOW and val.  
             A singe-valued case label.  
             A case range.  We can only handle integer ranges.  

References function::calls_setjmp, cfun, gimple_call_flags(), gimple_has_side_effects(), and function::has_nonlocal_label.

static eh_region find_outermost_region_in_block ( struct function src_cfun,
basic_block  bb,
eh_region  region 
   Examine the statements in BB (which is in SRC_CFUN); find and return
   the outermost EH region.  Use REGION as the incoming base EH region.  
edge find_taken_edge ( )
   Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
   predicate VAL, return the edge that will be taken out of the block.
   If VAL does not match a unique edge, NULL is returned.  
         Only optimize if the argument is a label, if the argument is
         not a label then we can not construct a proper CFG.

         It may be the case that we only need to allow the LABEL_REF to
         appear inside an ADDR_EXPR, but we also allow the LABEL_REF to
         appear inside a LABEL_EXPR just to be safe.  

References gimple_debug_bb().

Referenced by optimize_stmt().

static edge find_taken_edge_computed_goto ( basic_block  ,
static edge find_taken_edge_computed_goto ( )
   Given a constant value VAL and the entry block BB to a GOTO_EXPR
   statement, determine which of the outgoing edges will be taken out of the
   block.  Return NULL if either edge may be taken.  

References current_function_name().

static edge find_taken_edge_cond_expr ( basic_block  ,
static edge find_taken_edge_cond_expr ( )
   Given a constant value VAL and the entry block BB to a COND_EXPR
   statement, determine which of the two edges will be taken out of the
   block.  Return NULL if either edge may be taken.  
static edge find_taken_edge_switch_expr ( basic_block  ,
static edge find_taken_edge_switch_expr ( )
   Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
   statement, determine which edge will be taken out of the block.  Return
   NULL if any edge may be taken.  

References dump_cfg_stats().

static gimple first_non_label_stmt ( basic_block  )
static gimple first_non_label_stmt ( )
   Return the first non-label statement in basic block BB.  
gimple first_stmt ( )
   Return the first statement in basic block BB.  

References error().

Referenced by phi_alternatives_equal(), vect_get_store_cost(), and vect_model_promotion_demotion_cost().

static void fixup_loop_arrays_after_move ( struct function fn1,
struct function fn2,
struct loop loop 
   Fixup the loop arrays and numbers after moving LOOP and its subloops
   from FN1 to FN2.  
     Discard it from the old loop array.  
     Place it in the new loop array, assigning it a new number.  
     Recurse to children.  

Referenced by move_stmt_eh_region_tree_nr().

void fold_cond_expr_cond ( void  )
   Fold COND_EXPR_COND of each COND_EXPR.  
static bool gate_warn_unused_result ( )
void gather_blocks_in_sese_region ( basic_block  entry,
basic_block  exit,
vec< basic_block > *  bbs_p 
   Add all the blocks dominated by ENTRY to the array BBS_P.  Stop
   adding blocks when the dominator traversal reaches EXIT.  This
   function silently assumes that ENTRY strictly dominates EXIT.  

Referenced by create_loads_and_stores_for_name(), and move_stmt_r().

static tree get_cases_for_edge ( )
   If we are inside a {start,end}_recording_cases block, then return
   a chain of CASE_LABEL_EXPRs from T which reference E.

   Otherwise return NULL.  
     If we are not recording cases, then we do not have CASE_LABEL_EXPR
     chains available.  Return NULL so the caller can detect this case.  
     If we did not find E in the hash table, then this must be the first
     time we have been queried for information about E & T.  Add all the
     elements from T to the hash table then perform the query again.  
         Add it to the chain of CASE_LABEL_EXPRs referencing E, or create
         a new chain.  
static void gimple_account_profile_record ( basic_block  bb,
int  after_pass,
struct profile_record record 
   Do book-keeping of basic block BB for the profile consistency checker.
   If AFTER_PASS is 0, do pre-pass accounting, or if AFTER_PASS is 1
   then do post-pass accounting.  Store the counting in RECORD.  
static bool gimple_block_ends_with_call_p ( )
   Return true if BB ends with a call, possibly followed by some
   instructions that must stay with the call.  Return false,

References gimple_purge_dead_abnormal_call_edges().

static bool gimple_block_ends_with_condjump_p ( )
   Return true if BB ends with a conditional branch.  Return false,
tree gimple_block_label ( )
   Return a non-special label in the head of basic block BLOCK.
   Create one if it doesn't exist.  

Referenced by lower_eh_constructs().

static bool gimple_can_duplicate_bb_p ( )
   Return true if basic_block can be duplicated.  
static bool gimple_can_merge_blocks_p ( basic_block  ,
static bool gimple_can_merge_blocks_p ( )
   Checks whether we can merge block B into block A.  
     If A ends by a statement causing exceptions or something similar, we
     cannot merge the blocks.  
     Do not allow a block with only a non-local label to be merged.  
     Examine the labels at the beginning of B.  
         Do not remove user forced labels or for -O0 any user labels.  
     Protect the loop latches.  
     It must be possible to eliminate all phi nodes in B.  If ssa form
     is not up-to-date and a name-mapping is registered, we cannot eliminate
     any phis.  Symbols marked for renaming are never a problem though.  
         Technically only new names matter.  
     When not optimizing, don't merge if we'd lose goto_locus.  
static bool gimple_can_remove_branch_p ( )
   Returns true if it is possible to remove edge E by redirecting
   it to the destination of the other edge from E->src.  
void gimple_debug_bb ( )
   Dump a basic block on stderr.  

Referenced by find_taken_edge().

basic_block gimple_debug_bb_n ( )
   Dump basic block with index N on stderr.  
void gimple_debug_cfg ( )
   Dump the CFG on stderr.

   FLAGS are the same used by the tree dumping functions
   (see TDF_* in dumpfile.h).  
void gimple_dump_cfg ( )
   Dump the program showing basic block boundaries on the given FILE.

   FLAGS are the same used by the tree dumping functions (see TDF_* in
static basic_block gimple_duplicate_bb ( )
   Create a duplicate of the basic block BB.  NOTE: This does not
   preserve SSA form.  
     Copy the PHI nodes.  We ignore PHI node arguments here because
     the incoming edges have not been setup yet.  
         Don't duplicate label debug stmts.  
         Create a new copy of STMT and duplicate STMT's virtual
         When copying around a stmt writing into a local non-user
         aggregate, make sure it won't share stack slot with other
         Create new names for all the definitions created by COPY and
         add replacement mappings for each new name.  
bool gimple_duplicate_sese_region ( edge  entry,
edge  exit,
basic_block region,
unsigned  n_region,
basic_block region_copy,
bool  update_dominance 
   Duplicates a REGION (set of N_REGION basic blocks) with just a single
   important exit edge EXIT.  By important we mean that no SSA name defined
   inside region is live over the other exit edges of the region.  All entry
   edges to the region must go to ENTRY->dest.  The edge ENTRY is redirected
   to the duplicate of the region.  Dominance and loop information is
   updated if UPDATE_DOMINANCE is true, but not the SSA web.  If
   UPDATE_DOMINANCE is false then we assume that the caller will update the
   dominance information after calling this function.  The new basic
   blocks are stored to REGION_COPY in the same order as they had in REGION,
   provided that REGION_COPY is not NULL.
   The function returns false if it is unable to copy the region,
   true otherwise.  
     Some sanity checking.  Note that we do not check for all possible
     missuses of the functions.  I.e. if you ask to copy something weird,
     it will work, but the state of structures probably will not be
         We do not handle subloops, i.e. all the blocks must belong to the
         same loop.  
     In case the function is used for loop header copying (which is the primary
     use), ensure that EXIT and its copy will be new latch and entry edges.  
     Record blocks outside the region that are dominated by something
         Fix up corner cases, to avoid division by zero or creation of negative
         Fix up corner cases, to avoid division by zero or creation of negative
     Redirect the entry and add the phi node arguments.  
     Concerning updating of dominators:  We must recount dominators
     for entry block and its copy.  Anything that is outside of the
     region, but was dominated by something inside needs recounting as
     Add the other PHI node arguments.  
bool gimple_duplicate_sese_tail ( edge  entry,
edge  exit,
basic_block region,
unsigned  n_region,
basic_block region_copy 

Duplicates REGION consisting of N_REGION blocks. The new blocks are stored to REGION_COPY in the same order in that they appear in REGION, if REGION_COPY is not NULL. ENTRY is the entry to the region, EXIT an exit from it. The condition guarding EXIT is moved to ENTRY. Returns true if duplication succeeds, false otherwise.

For example,

some_code; if (cond) A; else B;

is transformed to

if (cond) { some_code; A; } else { some_code; B; }

     Record blocks outside the region that are dominated by something
         Fix up corner cases, to avoid division by zero or creation of negative
         Fix up corner cases, to avoid division by zero or creation of negative
     Create the switch block, and put the exit condition to it.  
     Register the new edge from SWITCH_BB in loop exit lists.  
     Add the PHI node arguments.  
     Get rid of now superfluous conditions and associated edges (and phi node
     The latch of ORIG_LOOP was copied, and so was the backedge 
     to the original header.  We redirect this backedge to EXIT_BB.  
     Anything that is outside of the region, but was dominated by something
     inside needs to update dominance info.  
     Update the SSA web.  

Referenced by create_loop_fn().

static bool gimple_empty_block_p ( )
   Return TRUE if block BB has no executable statements, otherwise return
     BB must have no executable statements.  
static void gimple_execute_on_growing_pred ( )
   This function is called whenever a new edge is created or
static void gimple_execute_on_shrinking_pred ( )
   This function is called immediately before edge E is removed from
   the edge vector E->dest->preds.  

References gimple_location(), and warning_at().

static int gimple_flow_call_edges_add ( )
   Add fake edges to the function exit for any non constant and non
   noreturn calls (or noreturn calls with EH/abnormal edges),
   volatile inline assembly in the bitmap of blocks specified by BLOCKS
   or to the whole CFG if BLOCKS is zero.  Return the number of blocks
   that were split.

   The goal is to expose cases in which entering a basic block does
   not imply that all subsequent instructions must be executed.  
     In the last basic block, before epilogue generation, there will be
     a fallthru edge to EXIT.  Special care is required if the last insn
     of the last basic block is a call because make_edge folds duplicate
     edges, which would result in the fallthru edge also being marked
     fake, which would result in the fallthru edge being removed by
     remove_fake_edges, which would result in an invalid CFG.

     Moreover, we can't elide the outgoing fake edge, since the block
     profiler needs to take this into account in order to solve the minimal
     spanning tree in the case that the call doesn't return.

     Handle this by adding a dummy instruction in a new last basic block.  
     Now add fake edges to the function exit for any non constant
     calls since there is no way that we can determine if they will
     return or not...  
                     The handling above of the final block before the
                     epilogue should be enough to verify that there is
                     no edge to the exit block in CFG already.
                     Calling make_edge in such case would cause us to
                     mark that edge as fake and remove it later.  
                     Note that the following may create a new basic block
                     and renumber the existing basic blocks.  
static void gimple_lv_add_condition_to_bb ( basic_block  first_head,
basic_block  second_head,
basic_block  cond_bb,
void *  cond_e 
   Adds a if else statement to COND_BB with condition COND_EXPR.
   SECOND_HEAD is the destination of the THEN and FIRST_HEAD is
   the destination of the ELSE part.  
     Build new conditional expr 
     Add new cond in cond_bb.  
     Adjust edges appropriately to connect new head with first head
     as well as second head.  
static void gimple_lv_adjust_loop_header_phi ( basic_block  first,
basic_block  second,
basic_block  new_head,
edge  e 
   Adjust phi nodes for 'first' basic block.  'second' basic block is a copy
   of 'first'. Both of them are dominated by 'new_head' basic block. When
   'new_head' was created by 'second's incoming edge it received phi arguments
   on the edge by split_edge(). Later, additional edge 'e' was created to
   connect 'new_head' and 'first'. Now this routine adds phi args on this
   additional edge 'e' that new_head to second edge received as part of edge
     Because NEW_HEAD has been created by splitting SECOND's incoming
     edge, we should always have an edge from NEW_HEAD to SECOND.  
     Browse all 'second' basic block phi nodes and add phi args to
     edge 'e' for 'first' head. PHI args are always in correct order.  
static void gimple_make_forwarder_block ( edge  )
static void gimple_make_forwarder_block ( )
   Updates phi nodes after creating a forwarder block joined
   by edge FALLTHRU.  
     If we redirected a branch we must create new PHI nodes at the
     start of BB.  
     Add the arguments we have stored on edges.  

References create_empty_bb(), walk_stmt_info::gsi, gsi_end_p(), gsi_next(), gsi_split_seq_before(), gsi_start_bb(), gsi_stmt(), edge_def::src, and basic_block_def::succs.

static void gimple_merge_blocks ( basic_block  ,
   Flowgraph optimization and cleanup.  
static void gimple_merge_blocks ( )
   Merge block B into block A.  
     Remove all single-valued PHI nodes from block B of the form
     V_i = PHI <V_j> by propagating V_j to all the uses of V_i.  
         In case we maintain loop closed ssa form, do not propagate arguments
         of loop exit phi nodes.  
             Note that just emitting the copies is fine -- there is no problem
             with ordering of phi nodes.  This is because A is the single
             predecessor of B, therefore results of the phi nodes cannot
             appear as arguments of the phi nodes.  
             If we deal with a PHI for virtual operands, we can simply
             propagate these without fussing with folding or updating
             the stmt.  
     Ensure that B follows A.  
     Remove labels from B and set gimple_bb to A for other statements.  
             Now that we can thread computed gotos, we might have
             a situation where we have a forced label in block B
             However, the label at the start of block B might still be
             used in other ways (think about the runtime checking for
             Fortran assigned gotos).  So we can not just delete the
             label.  Instead we move the label to the start of block A.  
             Other user labels keep around in a form of a debug stmt.  
     Merge the sequences.  

References edge_def::dest, edge_def::flags, and basic_block_def::succs.

static bool gimple_move_block_after ( )
   Moves basic block BB after block AFTER.  
bool gimple_purge_all_dead_abnormal_call_edges ( )
   Purge dead abnormal call edges from basic block listed in BLOCKS.  
         Earlier gimple_purge_dead_abnormal_call_edges could have removed
         this basic block already.  

References do_warn_unused_result(), g, gimple_bind_body(), gimple_catch_handler(), gimple_eh_filter_failure(), gimple_try_cleanup(), gimple_try_eval(), gsi_end_p(), gsi_next(), and gsi_stmt().

bool gimple_purge_all_dead_eh_edges ( )
   Purge dead EH edges from basic block listed in BLOCKS.  
         Earlier gimple_purge_dead_eh_edges could have removed
         this basic block already.  

References edge_def::flags.

bool gimple_purge_dead_abnormal_call_edges ( )
   Purge dead abnormal call edges from basic block BB.  

Referenced by gimple_block_ends_with_call_p().

bool gimple_purge_dead_eh_edges ( )
static edge gimple_redirect_edge_and_branch ( edge  ,
static edge gimple_redirect_edge_and_branch ( )
   Redirect E to DEST.  Return NULL on failure.  Otherwise, return the
   edge representing the redirected branch.  
         For COND_EXPR, we only need to redirect the edge.  
         No non-abnormal edges should lead from a non-simple goto, and
         simple ones should be represented implicitly.  
           If we have a list of cases associated with E, then use it
           as it's a lot faster than walking the entire case vector.  
               If there was already an edge in the CFG, then we need
               to move all the cases associated with E to E2.  
           If we didn't find any label matching the former edge in the
           asm labels, we must be redirecting the fallthrough
         The edges from OMP constructs can be simply redirected.  
         The ABORT edge has a stored label associated with it, otherwise
         the edges are simply redirectable.  
         Otherwise it must be a fallthru edge, and we don't need to
         do anything besides redirecting it.  
     Update/insert PHI nodes as necessary.  
     Now update the edges in the CFG.  

References cfun, copy(), create_empty_bb(), create_new_def_for(), create_phi_node(), get_base_address(), gimple_copy(), gimple_debug_bind_get_var(), gimple_debug_bind_p(), gimple_duplicate_stmt_histograms(), gimple_get_lhs(), gimple_phi_result(), gimple_phi_result_ptr(), gimple_set_uid(), gimple_uid(), walk_stmt_info::gsi, gsi_end_p(), gsi_insert_after(), GSI_NEW_STMT, gsi_next(), gsi_start_bb(), gsi_stmt(), maybe_duplicate_eh_stmt(), and phi_nodes().

static basic_block gimple_redirect_edge_and_branch_force ( )
   Simple wrapper, as we can always redirect fallthru edges.  

References edge_def::dest, and basic_block_def::loop_father.

static basic_block gimple_split_block ( )
   Splits basic block BB after statement STMT (but at least after the
   labels).  If STMT is NULL, BB is split just after the labels.  
     Redirect the outgoing edges.  
     Move everything from GSI to the new basic block.  
     Split the statement list - avoid re-creating new containers as this
     brings ugly quadratic memory consumption in the inliner.
     (We are still quadratic since we need to update stmt BB pointers,

References edge_def::dest, and loop::header.

static basic_block gimple_split_block_before_cond_jump ( )
   Split a basic block if it ends with a conditional branch and if the
   other part of the block is not empty.  
static basic_block gimple_split_edge ( )
   Split a (typically critical) edge EDGE_IN.  Return the new block.
   Abort on abnormal edges.  
     Abnormal edges cannot be split.  

References error().

static edge gimple_try_redirect_by_replacing_jump ( edge  ,
static edge gimple_try_redirect_by_replacing_jump ( )
   Attempt to perform edge redirection by replacing a possibly complex
   jump instruction by a goto or by removing the jump completely.
   This can apply only if all edges now point to the same block.  The
   parameters and return values are equivalent to
     We can replace or remove a complex jump only when we have exactly
     two edges.  
         Verify that all targets will be TARGET.  Specifically, the
         edge that is not E must also go to TARGET.  
static int gimple_verify_flow_info ( )
   Verifies that the flow information is OK.  
         Skip labels on the start of basic block.  
         Verify that body of basic block BB is free of control flow.  
             Verify that there are no edges with EDGE_TRUE/FALSE_FLAG set
             after anything else but if statement.  
                 FIXME.  We should double check that the labels in the
                 destination blocks have their address taken.  
             ... fallthru ... 
               Mark all the destination basic blocks.  
               Verify that the case labels are sorted.  
               VRP will remove the default case if it can prove it will
               never be executed.  So do not verify there always exists
               a default case here.  
               Check that we have all of them.  
tree gimplify_build1 ( gimple_stmt_iterator gsi,
enum tree_code  code,
tree  type,
tree  a 
   Build a unary operation and gimplify it.  Emit code before GSI.
   Return the gimple_val holding the result.  

Referenced by expand_complex_libcall().

tree gimplify_build2 ( gimple_stmt_iterator gsi,
enum tree_code  code,
tree  type,
tree  a,
tree  b 
   Build a binary operation and gimplify it.  Emit code before GSI.
   Return the gimple_val holding the result.  

Referenced by add_rshift(), and expand_complex_libcall().

tree gimplify_build3 ( gimple_stmt_iterator gsi,
enum tree_code  code,
tree  type,
tree  a,
tree  b,
tree  c 
   Build a ternary operation and gimplify it.  Emit code before GSI.
   Return the gimple_val holding the result.  

References current_ir_type(), edge_def::dest, edge_def::edge_def_insns::g, edge_def::goto_locus, gt_pch_nx(), edge_def::insns, IR_GIMPLE, edge_def::edge_def_insns::r, and edge_def::src.

void group_case_labels ( void  )
   Look for blocks ending in a multiway branch (a GIMPLE_SWITCH),
   and scan the sorted vector of cases.  Combine the ones jumping to the
   same label.  

References edge_def::flags, gimple_phi_arg_edge(), replace_exp(), and virtual_operand_p().

void group_case_labels_stmt ( )
   Scan the sorted vector of cases in STMT (a GIMPLE_SWITCH) and combine
   the ones jumping to the same label.
   Eg. three separate entries 1: 2: 3: become one entry 1..3:  
     Look for possible opportunities to merge cases.  
         Discard cases that have the same destination as the
         default case.  
         Try to merge case labels.  Break out when we reach the end
         of the label vector or when we cannot merge the next case
         label with the current one.  
             Merge the cases if they jump to the same place,
             and their ranges are consecutive.  
     Compress the case labels in the label vector, and adjust the
     length of the vector.  
void gt_ggc_mx ( tree )
   Garbage collection support for edge_def.  
void gt_ggc_mx ( gimple )
void gt_ggc_mx ( rtx )
void gt_ggc_mx ( basic_block )
void gt_ggc_mx ( )
void gt_pch_nx ( tree )
   PCH support for edge_def.  
void gt_pch_nx ( gimple )
void gt_pch_nx ( rtx )
void gt_pch_nx ( basic_block )
void gt_pch_nx ( )
void init_empty_tree_cfg ( void  )
void init_empty_tree_cfg_for_function ( )
     Initialize the basic block array.  
     Build a mapping of labels to their associated blocks.  
bool is_ctrl_altering_stmt ( )
   Return true if T is a statement that may alter the flow of control
   (e.g., a call to a non-returning function).  
           A call alters control flow if it can make an abnormal goto.  
           A call also alters control flow if it does not return.  
           TM ending statements have backedges out of the transaction.
           Return true so we split the basic block containing them.
           Note that the TM_BUILTIN test is merely an optimization.  
           BUILT_IN_RETURN call is same as return statement.  
         EH_DISPATCH branches to the individual catch handlers at
         this level of a try or allowed-exceptions region.  It can
         fallthru to the next statement as well.  
         OpenMP directives alter control flow.  
         A transaction start alters control flow.  
     If a statement can throw, it alters control flow.  
bool is_ctrl_stmt ( )
   Return true if T represents a stmt that always transfers control.  

References gsi_end_p(), gsi_next(), gsi_start_bb(), and gsi_stmt().

Referenced by create_rdg_edges_for_scalar(), and gsi_for_stmt().

basic_block label_to_block_fn ( )
   Return the basic block holding label DEST.  
     We would die hard when faced by an undefined label.  Emit a label to
     the very first basic block.  This will hopefully make even the dataflow
     and undefined variable warnings quite right.  
gimple last_and_only_stmt ( )
   Return the last statement of an otherwise empty block.  Return NULL
   if the block is totally empty, or if it contains more than one
     Empty statements should no longer appear in the instruction stream.
     Everything that might have appeared before should be deleted by
     remove_useless_stmts, and the optimizers should just gsi_remove
     instead of smashing with build_empty_stmt.

     Thus the only thing that should appear here in a block containing
     one executable statement is a label.  
static tree main_block_label ( )
   Given LABEL return the first label in the same basic block.  
     label_to_block possibly inserted undefined label into the chain.  

Referenced by cleanup_dead_labels(), make_gimple_asm_edges(), and make_goto_expr_edges().

void make_abnormal_goto_edges ( )
   Create edges for an abnormal goto statement at block BB.  If FOR_CALL
   is true, the source statement is a CALL_EXPR instead of a GOTO_EXPR.  
             Make an edge to every label block that has been marked as a
             potential target for a computed goto or a non-local goto.  
             Make an edge to every setjmp-like call.  
static void make_blocks ( gimple_seq  )
   Basic blocks and flowgraphs.  
static void make_blocks ( )
   Build a flowgraph for the sequence of stmts SEQ.  
         If the statement starts a new basic block or if we have determined
         in a previous pass that we need to create a new block for STMT, do
         so now.  
         Now add STMT to BB and create the subgraphs for special statement
         If STMT is a basic block terminator, set START_NEW_BLOCK for the
         next iteration.  
             If the stmt can make abnormal goto use a new temporary
             for the assignment to the LHS.  This makes sure the old value
             of the LHS is available on the abnormal edge.  Otherwise
             we will end up with overlapping life-ranges for abnormal
             SSA names.  

References create_tmp_var(), gimple_block(), gimple_get_lhs(), gimple_location(), gimple_set_block(), gimple_set_lhs(), gimple_set_location(), gsi_insert_after(), and GSI_SAME_STMT.

static void make_cond_expr_edges ( basic_block  )
static void make_cond_expr_edges ( )
   Create the edges for a GIMPLE_COND starting at block BB.  
     Entry basic blocks for each component.  
     We do not need the labels anymore.  
static void make_edges ( void  )
   Join all the blocks in the flowgraph.  
     Create an edge from entry to the first block with executable
     statements in it.  
     Traverse the basic block array placing edges.  
                 If this function receives a nonlocal goto, then we need to
                 make edges from this call site to all the nonlocal goto
                 If this statement has reachable exception handlers, then
                 create abnormal edges to them.  
                 BUILTIN_RETURN is really a return statement.  
                 Some calls are known not to return.  
                  A GIMPLE_ASSIGN may throw internally and thus be considered
     Fold COND_EXPR_COND of each COND_EXPR.  
static void make_gimple_asm_edges ( basic_block  )
static void make_gimple_asm_edges ( )
static void make_gimple_switch_edges ( basic_block  )
static void make_gimple_switch_edges ( )
   Create the edges for a GIMPLE_SWITCH starting at block BB.  
static void make_goto_expr_edges ( basic_block  )
static void make_goto_expr_edges ( )
   Create edges for a goto statement at block BB.  
     A simple GOTO creates normal edges.  
     A computed GOTO creates abnormal edges.  

References cfun, function::eh, ERT_CLEANUP, ERT_MUST_NOT_THROW, eh_landing_pad_d::index, eh_status::lp_array, main_block_label(), eh_landing_pad_d::post_landing_pad, eh_region_d::type, and vec_safe_iterate().

gimple_opt_pass* make_pass_build_cfg ( )

References gsi_last_bb(), and last.

gimple_opt_pass* make_pass_fixup_cfg ( )
gimple_opt_pass* make_pass_split_crit_edges ( )
gimple_opt_pass* make_pass_warn_function_return ( )
gimple_opt_pass* make_pass_warn_unused_result ( )
static void move_block_to_fn ( struct function dest_cfun,
basic_block  bb,
basic_block  after,
bool  update_edge_count_p,
struct move_stmt_d d 
   Move basic block BB from function CFUN to function DEST_FN.  The
   block is moved out of the original linked list and placed after
   block AFTER in the new list.  Also, the block is removed from the
   original array of blocks and placed in DEST_FN's array of blocks.
   If UPDATE_EDGE_COUNT_P is true, the edge counts on both CFGs is
   updated to reflect the moved edges.

   The local variables are remapped to new instances, VARS_MAP is used
   to record the mapping.  
     Remove BB from dominance structures.  
     Move BB from its current loop to the copy in the new function.  
     Link BB to the new linked list.  
     Update the edge count in the corresponding flowgraphs.  
     Remove BB from the original basic block array.  
     Grow DEST_CFUN's basic block array if needed.  
     Remap the variables in phi nodes.  
             Remove the phi nodes for virtual operands (alias analysis will be
             run for the new function, anyway).  
         We cannot leave any operands allocated from the operand caches of
         the current function.  
basic_block move_sese_region_to_fn ( struct function dest_cfun,
basic_block  entry_bb,
basic_block  exit_bb,
tree  orig_block 
   Move a single-entry, single-exit region delimited by ENTRY_BB and
   EXIT_BB to function DEST_CFUN.  The whole region is replaced by a
   single basic block in the original CFG and the new basic block is
   returned.  DEST_CFUN must not have a CFG yet.

   Note that the region need not be a pure SESE region.  Blocks inside
   the region may contain calls to abort/exit.  The only restriction
   is that ENTRY_BB should be the only entry point and it must
   dominate EXIT_BB.

   Change TREE_BLOCK of all statements in ORIG_BLOCK to the new
   functions outermost BLOCK, move all subblocks of ORIG_BLOCK
   to the new function.

   All local variables referenced in the region are assumed to be in
   the corresponding BLOCK_VARS and unexpanded variable lists
   associated with DEST_CFUN.  
     If ENTRY does not strictly dominate EXIT, this cannot be an SESE
     Collect all the blocks in the region.  Manually add ENTRY_BB
     because it won't be added by dfs_enumerate_from.  
     The blocks that used to be dominated by something in BBS will now be
     dominated by the new block.  
     Detach ENTRY_BB and EXIT_BB from CFUN->CFG.  We need to remember
     the predecessor edges to ENTRY_BB and the successor edges to
     EXIT_BB so that we can re-attach them to the new basic block that
     will replace the region.  
     Switch context to the child function to initialize DEST_FN's CFG.  
     Initialize EH information for the new function.  
     Initialize an empty loop tree.  
     Move the outlined loop tree part.  
                 If the SESE region contains some bbs ending with
                 a noreturn call, those are considered to belong
                 to the outermost loop in saved_cfun, rather than
                 the entry_bb's loop_father.  
         Remove loop exits from the outlined region.  
     Adjust the number of blocks in the tree root of the outlined part.  
     Setup a mapping to be used by move_block_to_fn.  
     Move blocks from BBS into DEST_CFUN.  
         No need to update edge counts on the last block.  It has
         already been updated earlier when we detached the region from
         the original CFG.  
     Loop sizes are no longer correct, fix them up.  
     Rewire BLOCK_SUBBLOCKS of orig_block.  
     Rewire the entry and exit blocks.  The successor to the entry
     block turns into the successor of DEST_FN's ENTRY_BLOCK_PTR in
     the child function.  Similarly, the predecessor of DEST_FN's
     EXIT_BLOCK_PTR turns into the predecessor of EXIT_BLOCK_PTR.  We
     need to switch CFUN between DEST_CFUN and SAVED_CFUN so that the
     various CFG manipulation function get to the right CFG.

     FIXME, this is silly.  The CFG ought to become a parameter to
     these helpers.  
     Back in the original function, the SESE region has disappeared,
     create a new basic block in its place.  

References gimple_body(), gimple_seq_first_stmt(), gimple_seq_last_stmt(), and print_gimple_seq().

static int move_stmt_eh_region_nr ( )
   Helper for move_stmt_r.  Given an EH region number for the source
   function, map that to the duplicate EH regio number in the dest.  
static tree move_stmt_eh_region_tree_nr ( )
static tree move_stmt_op ( )
   Helper for move_block_to_fn.  Set TREE_BLOCK in every expression
   contained in *TP if it has been ORIG_BLOCK previously and change the
   DECL_CONTEXT of every local variable referenced in *TP.  
             Replace T with its duplicate.  T should no longer appear in the
             parent function, so this looks wasteful; however, it may appear
             in referenced_vars, and more importantly, as virtual operands of
             statements, and in alias lists of other variables.  It would be
             quite difficult to expunge it from all those places.  ??? It might
             suffice to do this for addressable variables.  

References eh_region_outermost(), get_eh_region_from_lp_number_fn(), gsi_end_p(), gsi_next(), gsi_start_bb(), gsi_stmt(), lookup_stmt_eh_lp_fn(), and si.

static tree move_stmt_r ( gimple_stmt_iterator gsi_p,
bool *  handled_ops_p,
struct walk_stmt_info wi 
   Like move_stmt_op, but for gimple statements.

   Helper for move_block_to_fn.  Set GIMPLE_BLOCK in every expression
   contained in the current statement in *GSI_P and change the
   DECL_CONTEXT of every local variable referenced in the current
         Remap the region numbers for __builtin_eh_{pointer,filter}.  
             Do not remap variables inside OMP directives.  Variables
             referenced in clauses and directive header belong to the
             parent function and should not be moved into the child

References cfun, edge_def::dest, dominated_by_p(), ei_safe_edge(), edge_def::flags, gather_blocks_in_sese_region(), get_dominated_by_region(), get_immediate_dominator(), get_loop(), basic_block_def::loop_father, loop::num_nodes, basic_block_def::preds, edge_def::probability, remove_edge(), edge_def::src, and basic_block_def::succs.

static bool need_fake_edge_p ( )
   Return true if we need to add fake edge to exit at statement T.
   Helper function for gimple_flow_call_edges_add.  
     NORETURN and LONGJMP calls already have an edge to exit.
     CONST and PURE calls do not need one.
     We don't currently check for CONST and PURE here, although
     it would be a good idea, because those attributes are
     figured out from the RTL in mark_constant_function, and
     the counter incrementation code from -fprofile-arcs
     leads to different results from -fbranch-probabilities.  
         fork() doesn't really return twice, but the effect of
         wrapping it in __gcov_fork() which calls __gcov_flush()
         and clears the counters before forking has the same
         effect as returning twice.  Force a fake edge.  
static tree new_label_mapper ( )
static int next_discriminator_for_locus ( )
   Find the next available discriminator value for LOCUS.  The
   discriminator distinguishes among several basic blocks that
   share a common locus, allowing for more accurate sample-based

References edge_def::dest, basic_block_def::discriminator, first, first_non_label_stmt(), last_stmt(), and same_line_p().

void notice_special_calls ( )
   T is CALL_EXPR.  Set current_function_calls_* flags.  
static bool one_pointer_to_useless_type_conversion_p ( )
   Returns true if there is one pointer type in TYPE_POINTER_TO (SRC_OBJ)
   list of pointer-to types that is trivially convertible to DEST.  
static void print_loop ( )
   Pretty print LOOP on FILE, indented INDENT spaces.  Following
   VERBOSITY level this outputs the contents of the loop, or just its
     Print loop's header.  
     Print loop's body.  

References bitmap_set_bit(), edge_def::dest, basic_block_def::index, and basic_block_def::succs.

static void print_loop_and_siblings ( FILE *  file,
struct loop loop,
int  indent,
int  verbosity 
   Print the LOOP and its sibling loops on FILE, indented INDENT
   spaces.  Following VERBOSITY level this outputs the contents of the
   loop, or just its structure.  
void print_loops ( )
   Follow a CFG edge from the entry point of the program, and on entry
   of a loop, pretty print the loop structure on FILE.  

References ei_next(), edge_def::flags, and remove_edge_and_dominated_blocks().

void print_loops_bb ( )
   Print to FILE the basic block BB following the VERBOSITY level.  
     Print basic_block's header.  
     Print basic_block's body.  
static void print_pred_bbs ( )
   Print on FILE the indexes for the predecessors of basic_block BB.  

References df, and vNULL.

static void print_succ_bbs ( )
   Print on FILE the indexes for the successors of basic_block BB.  

References remove_edge().

static bool recording_case_labels_p ( )
   Return nonzero if we are recording information for case labels.  

References last_stmt().

static void reinstall_phi_args ( )
   Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE.  

Referenced by stmt_starts_bb_p().

static void remove_bb ( basic_block  )
static void remove_bb ( )
   Remove statements of basic block BB.  
         If a loop gets removed, clean up the information associated
         with it.  
     Remove all the instructions in the block.  
         Walk backwards so as to get a chance to substitute all
         released DEFs into debug stmts.  See
         eliminate_unnecessary_stmts() in tree-ssa-dce.c for more
                 A non-reachable non-local label may still be referenced.
                 But it no longer needs to carry the extra semantics of
                 Release SSA definitions if we are in SSA.  Note that we
                 may be called when not in SSA.  For example,
                 final_cleanup calls this function via
void remove_edge_and_dominated_blocks ( )
   Removes edge E and all the blocks dominated by it, and updates dominance
   information.  The IL in E->src needs to be updated separately.
   If dominance info is not available, only the edge E is removed.
     No updating is needed for edges to exit.  
     First, we find the basic blocks to remove.  If E->dest has a predecessor
     that is not dominated by E->dest, then this set is empty.  Otherwise,
     all the basic blocks dominated by E->dest are removed.

     Also, to DF_IDOM we store the immediate dominators of the blocks in
     the dominance frontier of E (i.e., of the successors of the
     removed blocks, if there are any, and of E->dest otherwise).  
         Record the set of the altered basic blocks.  
     Remove E and the cancelled blocks.  
         Walk backwards so as to get a chance to substitute all
         released DEFs into debug stmts.  See
         eliminate_unnecessary_stmts() in tree-ssa-dce.c for more
     Update the dominance information.  The immediate dominator may change only
     for blocks whose immediate dominator belongs to DF_IDOM:

     Suppose that idom(X) = Y before removal of E and idom(X) != Y after the
     removal.  Let Z the arbitrary block such that idom(Z) = Y and
     Z dominates X after the removal.  Before removal, there exists a path P
     from Y to X that avoids Z.  Let F be the last edge on P that is
     removed, and let W = F->dest.  Before removal, idom(W) = Y (since Y
     dominates W, and because of P, Z does not dominate W), and W belongs to
     the dominance frontier of E.  Therefore, Y belongs to DF_IDOM.  

Referenced by print_loops(), and remove_fallthru_edge().

static void remove_phi_nodes_and_edges_for_unreachable_block ( )
   Remove PHI nodes associated with basic block BB and all edges out of BB.  
     Since this block is no longer reachable, we can just delete all
     of its PHI nodes.  
     Remove edges to BB's successors.  
static void replace_block_vars_by_duplicates ( tree  block,
struct pointer_map_t vars_map,
tree  to_context 
   Change DECL_CONTEXT of all BLOCK_VARS in block, including
static void replace_by_duplicate_decl ( tree tp,
struct pointer_map_t vars_map,
tree  to_context 
   Replaces *TP with a duplicate (belonging to function TO_CONTEXT).
   The duplicates are recorded in VARS_MAP.  
static void replace_loop_annotate ( )
   Search for ANNOTATE call with annot_expr_ivdep_kind; if found, remove
   it and set loop->safelen to INT_MAX.  We assume that the annotation
   comes immediately before the condition.  
     Remove IFN_ANNOTATE. Safeguard for the case loop->latch == NULL.  
static tree replace_ssa_name ( tree  name,
struct pointer_map_t vars_map,
tree  to_context 
   Creates an ssa name in TO_CONTEXT equivalent to NAME.
   VARS_MAP maps old ssa names and var_decls to the new ones.  

References function::cfg, cfun, gimple_label_label(), vec_safe_grow_cleared(), vec_safe_length(), and control_flow_graph::x_label_to_block_map.

void replace_uses_by ( )
   Replaces all uses of NAME by VAL.  
                     This can only occur for virtual operands, since
                     for the real ones SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
                     would prevent replacement.  
             Mark the block if we changed the last stmt in it.  
             FIXME.  It shouldn't be required to keep TREE_CONSTANT
             on ADDR_EXPRs up-to-date on GIMPLE.  Propagation will
             only change sth from non-invariant to invariant, and only
             when propagating constants.  
                   Operands may be empty here.  For example, the labels
                   of a GIMPLE_COND are nulled out following the creation
                   of the corresponding CFG edges.  
     Also update the trees stored in loop structures.  

Referenced by scev_reset().

static unsigned int run_warn_unused_result ( )
static bool same_line_p ( )
   Return TRUE if LOCUS1 and LOCUS2 refer to the same source line.  

Referenced by next_discriminator_for_locus().

bool simple_goto_p ( )
   Return true if T is a simple local goto.  

References edge_def::dest, find_edge(), edge_def::flags, basic_block_def::prev_bb, and edge_def::src.

Referenced by mark_stmt_if_obviously_necessary().

basic_block single_noncomplex_succ ( )
   Return the one of two successors of BB that is not reachable by a
   complex edge, if there is one.  Else, return BB.  We use
   this in optimizations that use post-dominators for their heuristics,
   to catch the cases in C++ where function calls are involved.  
static unsigned int split_critical_edges ( )
   Split all critical edges.  
     split_edge can redirect edges out of SWITCH_EXPRs, which can get
     expensive.  So we want to enable recording of edge to CASE_LABEL_EXPR
     mappings around the calls to split_edge.  
             PRE inserts statements to edges and expects that
             since split_critical_edges was done beforehand, committing edge
             insertions will not split more edges.  In addition to critical
             edges we must split edges that have multiple successors and
             end by control flow statements, such as RESX.
             Go ahead and split them too.  This matches the logic in

References builtin_decl_implicit(), gimple_build_call(), gsi_insert_after(), gsi_last_bb(), and GSI_NEW_STMT.

static basic_block split_edge_bb_loc ( )
   Returns the basic block after which the new basic block created
   by splitting edge EDGE_IN should be placed.  Tries to keep the new block
   near its "logical" location.  This is of most help to humans looking
   at debugging dumps.  

References error().

Referenced by stmt_starts_bb_p().

void start_recording_case_labels ( void  )
   Start recording information mapping edges to case labels.  
bool stmt_can_make_abnormal_goto ( )
   Return true if T can make an abnormal transfer of control flow.
   Transfers of control flow associated with EH are excluded.  

References gsi_end_p(), gsi_next(), gsi_start_bb(), gsi_stmt(), and is_gimple_debug().

Referenced by eliminate_avail().

bool stmt_ends_bb_p ( )
static bool stmt_starts_bb_p ( gimple  ,
   Various helpers.  
static bool stmt_starts_bb_p ( )
   Return true if STMT should start a new basic block.  PREV_STMT is
   the statement preceding STMT.  It is used when STMT is a label or a
   case label.  Labels should only start a new basic block if their
   previous statement wasn't a label.  Otherwise, sequence of labels
   would generate unnecessary basic blocks that only contain a single
     Labels start a new basic block only if the preceding statement
     wasn't a label of the same type.  This prevents the creation of
     consecutive blocks that have nothing but a single label.  
         Nonlocal and computed GOTO targets always start a new block.  
       setjmp acts similar to a nonlocal GOTO target and thus should
       start a new block.  

References edge_def::count, basic_block_def::count, create_empty_bb(), edge_def::dest, edge_def::flags, basic_block_def::frequency, make_edge(), edge_def::probability, redirect_edge_and_branch(), reinstall_phi_args(), and split_edge_bb_loc().

static bool tree_node_can_be_shared ( )
   Return true when the T can be shared.  
static bool valid_fixed_convert_types_p ( )
   Return true if TYPE1 is a fixed-point type and if conversions to and
   from TYPE2 can be handled by FIXED_CONVERT_EXPR.  

References debug_generic_expr(), and error().

static tree verify_address ( )
   Verify properties of the address expression T with base object BASE.  
static int verify_eh_throw_stmt_node ( )
static tree verify_expr ( )
   Callback for walk_tree, check that all elements with address taken are
   properly noticed as such.  The DATA is an int* that is 1 if TP was seen
   inside a PHI node.  
     Check operand N for being valid GIMPLE and give error MSG if not.  
           Skip any references (they will be checked when we recurse down the
           tree) and ensure that any variable used as a prefix is marked
         We have a nest of references.  Verify that each of the operands
         that determine where to reference is either a constant or a variable,
         verify that the base is valid, and then show we've already checked
         the subtrees.  
         PLUS_EXPR and MINUS_EXPR don't work on pointers, they should be done using
         Check to make sure the first operand is a pointer or reference type. 
         Check to make sure the second operand is a ptrofftype.  

References error().

static tree verify_expr_location ( )
   Called via walk_gimple_op.  Verify locations of expressions.  
static tree verify_expr_location_1 ( )
   Called via walk_tree.  Verify locations of expressions.  

References error(), gimple_label_label(), gsi_end_p(), gsi_next(), gsi_start_bb(), gsi_stmt(), basic_block_def::index, and print_generic_expr().

static tree verify_expr_no_block ( )
   Called via walk_tree.  Verify that expressions have no blocks.  

References error().

static bool verify_gimple_assign ( )
   Verify the contents of a GIMPLE_ASSIGN STMT.  Returns true when there
   is a problem, otherwise false.  

References error().

static bool verify_gimple_assign_binary ( )
   Verify a gimple assignment statement STMT with a binary rhs.
   Returns true if anything is wrong.  
     First handle operations that involve different types.  
           Shifts and rotates are ok on integral types, fixed point
           types and integer vector types.  
                   Vector shifts of vectors are also ok.  
           For shifting a vector of non-integral components we
           only allow shifting by a constant multiple of the element size.  
           Continue with generic binary expression handling.  
         Comparisons are also binary, but the result type is not
         connected to the operand types.  
         Continue with generic binary expression handling.  
static bool verify_gimple_assign_single ( )
   Verify a gimple assignment statement STMT with a single rhs.
   Returns true if anything is wrong.  
     Special codes we cannot handle via their class.  
           Technically there is no longer a need for matching types, but
           gimple hygiene asks for this check.  In LTO we can end up
           combining incompatible units and thus end up with addresses
           of globals that change their type to a common one.  
             For vector CONSTRUCTORs we require that either it is empty
             CONSTRUCTOR, or it is a CONSTRUCTOR of smaller vector elements
             (then the element count must be correct to cover the whole
             outer vector and index must be NULL on all elements, or it is
             a CONSTRUCTOR of scalar elements, where we as an exception allow
             smaller number of elements (assuming zero filling) and
             consecutive indexes as compared to NULL indexes (such
             CONSTRUCTORs can appear in the IL from FEs).  
static bool verify_gimple_assign_ternary ( )
   Verify a gimple assignment statement STMT with a ternary rhs.
   Returns true if anything is wrong.  
     First handle operations that involve different types.  

References debug_generic_stmt(), and error().

static bool verify_gimple_assign_unary ( )
   Verify a gimple assignment statement STMT with an unary rhs.
   Returns true if anything is wrong.  
     First handle conversions.  
           Allow conversions from pointer type to integral type only if
           there is no sign or zero extension involved.
           For targets were the precision of ptrofftype doesn't match that
           of pointers we need to allow arbitrary conversions to ptrofftype.  
           Allow conversion from integral to offset type and vice versa.  
           Otherwise assert we are converting between types of the
           same kind.  
     For the remaining codes assert there is no conversion involved.  
static bool verify_gimple_call ( )
   Verify the contents of a GIMPLE_CALL STMT.  Returns true when there
   is a problem, otherwise false.  
         ???  At least C++ misses conversions at assignments from
         void * call results.
         ???  Java is completely off.  Especially with functions
         returning java.lang.Object.
         For now simply allow arbitrary pointer type conversions.  
     If there is a static chain argument, this should not be an indirect
     call, and the decl should have DECL_STATIC_CHAIN set.  
     ???  The C frontend passes unpromoted arguments in case it
     didn't see a function declaration before the call.  So for now
     leave the call arguments mostly unverified.  Once we gimplify
     unit-at-a-time we have a chance to fix this.  
static bool verify_gimple_comparison ( )
   Verifies the gimple comparison with the result type TYPE and
   the operands OP0 and OP1.  
     For comparisons we do not have the operations type as the
     effective type the comparison is carried out in.  Instead
     we require that either the first operand is trivially
     convertible into the second, or the other way around.
     Because we special-case pointers to void we allow
     comparisons of pointers with the same mode as well.  
     The resulting type of a comparison may be an effective boolean type.  
     Or an integer vector type with the same size and element count
     as the comparison operand types.  
             The result of a vector comparison is of signed
             integral type.  
static bool verify_gimple_debug ( )
   Verify a gimple debug statement STMT.
   Returns true if anything is wrong.  
     There isn't much that could be wrong in a gimple debug stmt.  A
     gimple debug bind stmt, for example, maps a tree, that's usually
     a VAR_DECL or a PARM_DECL, but that could also be some scalarized
     component or member of an aggregate type, to another tree, that
     can be an arbitrary expression.  These stmts expand into debug
     insns, and are converted to debug notes by var-tracking.c.  
static bool verify_gimple_goto ( )
   Verify the contents of a GIMPLE_GOTO STMT.  Returns true when there
   is a problem, otherwise false.  
     ???  We have two canonical forms of direct goto destinations, a
     bare LABEL_DECL and an ADDR_EXPR of a LABEL_DECL.  

References error().

DEBUG_FUNCTION void verify_gimple_in_cfg ( )
   Verify the GIMPLE statements in the CFG of FN.  
     Collect all BLOCKs referenced by the BLOCK tree of FN.  
             Only PHI arguments have locations.  
             ???  Instead of not checking these stmts at all the walker
             should know its context via wi.  
             If the statement is marked as part of an EH region, then it is
             expected that the statement could throw.  Verify that when we
             have optimizations that simplify statements such that we prove
             that they cannot throw, that we update other data structures
             to match.  
DEBUG_FUNCTION void verify_gimple_in_seq ( )
   Verify the GIMPLE statements inside the statement list STMTS.  
static bool verify_gimple_in_seq_2 ( )
   Verify the GIMPLE statements inside the sequence STMTS.  
static bool verify_gimple_label ( )
   Verify a gimple label statement STMT.
   Returns true if anything is wrong.  

References gdbhooks::IDENTIFIER_NODE, and is_gimple_min_invariant().

static bool verify_gimple_phi ( )
   Verify the contents of a GIMPLE_PHI.  Returns true if there is a problem,
   and false otherwise.  
         Addressable variables do have SSA_NAMEs but they
         are not considered gimple values.  
static bool verify_gimple_return ( )
   Verify the contents of a GIMPLE_RETURN STMT.  Returns true when there
   is a problem, otherwise false.  
     We cannot test for present return values as we do not fix up missing
     return values from the original source.  
static bool verify_gimple_stmt ( )
   Verify the GIMPLE statement STMT.  Returns true if there is an
   error, otherwise false.  
       Tuples that do not have tree operands.  
         OpenMP directives are validated by the FE and never operated
         on by the optimizers.  Furthermore, GIMPLE_OMP_FOR may contain
         non-gimple expressions when the main index variable has had
         its address taken.  This does not affect the loop itself
         because the header of an GIMPLE_OMP_FOR is merely used to determine
         how to setup the parallel iteration.  

References walk_stmt_info::info, and verify_node_sharing_1().

static bool verify_gimple_switch ( )
   Verify the contents of a GIMPLE_SWITCH STMT.  Returns true when there
   is a problem, otherwise false.  
static bool verify_gimple_transaction ( gimple  )
static bool verify_gimple_transaction ( )
   Verify the contents of a GIMPLE_TRANSACTION.  Returns true if there
   is a problem, otherwise false.  
static bool verify_location ( )
   Verify if the location LOCs block is in BLOCKS.  
static tree verify_node_sharing ( )
   Called via walk_gimple_stmt.  Verify tree sharing.  

References error().

static tree verify_node_sharing_1 ( )
   Called via walk_tree.  Verify tree sharing.  

Referenced by verify_gimple_stmt().

static bool verify_types_in_gimple_min_lval ( )
   Verify if EXPR is either a GIMPLE ID or a GIMPLE indirect reference.
   Returns true if there is an error, otherwise false.  
     TARGET_MEM_REFs are strange beasts.  
     Memory references now generally can involve a value conversion.  

References debug_generic_stmt(), and error().

static bool verify_types_in_gimple_reference ( )
   Verify if EXPR is a valid GIMPLE reference expression.  If
   REQUIRE_LVALUE is true verifies it is an lvalue.  Returns true
   if there is an error, otherwise false.  
         Verify if the reference array element types are compatible.  
             For VIEW_CONVERT_EXPRs which are allowed here too, we only check
             that their operand is not an SSA name or an invariant when
             requiring an lvalue (this usually means there is a SRA or IPA-SRA
             bug).  Otherwise there is nothing to verify, gross mismatches at
             most invoke undefined behavior.  

References error().

Variable Documentation

struct cfg_stats_d cfg_stats

Referenced by debug_cfg_stats().

hash_table<locus_discrim_hasher> discriminator_per_locus
struct pointer_map_t* edge_to_cases
   This hash table allows us to efficiently lookup all CASE_LABEL_EXPRs
   which use a particular edge.  The CASE_LABEL_EXPRs are chained together
   via their CASE_CHAIN field, which we clear after we're done with the
   hash table to prevent problems with duplication of GIMPLE_SWITCHes.

   Access to this list of CASE_LABEL_EXPRs allows us to efficiently
   update the case vector in response to edge redirections.

   Right now this table is set up and torn down at key points in the
   compilation process.  It would be nice if we could make the table
   more persistent.  The key is getting notification of changes to
   the CFG (particularly edge removal, creation and redirection).  
bool eh_error_found
bool found_computed_goto
   Nonzero if we found a computed goto while building basic blocks.  
struct cfg_hooks gimple_cfg_hooks
   Hooks containers.  

Referenced by cfg_layout_rtl_register_cfg_hooks(), and set_cfg_hooks().

const int initial_cfg_capacity = 20

Control flow functions for trees. Copyright (C) 2001-2013 Free Software Foundation, Inc. Contributed by Diego Novillo dnovi.nosp@m.llo@.nosp@m.redha.nosp@m.t.co.nosp@m.m

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see http://www.gnu.org/licenses/.

   This file contains functions for building the Control Flow Graph (CFG)
   for a function tree.  
   Local declarations.  
   Initial capacity for the basic block array.  
struct label_record * label_for_bb
bitmap touched_switch_bbs
   If we record edge_to_cases, this bitmap will hold indexes
   of basic blocks that end in a GIMPLE_SWITCH which we touched
   due to edge manipulations.